The present invention relates to a small, portable memory device which has no conductive coupling means for external connection other than those for connection to a power source.
Conventional storage mediums which are portable and which permit writing and reading of data are generally those of the magnetic type such as magnetic tapes, cassette tapes, magnetic disks and floppy disks. This type of storage medium is advantageous in that the reading and writing of data is simple, the record is nonvolatile and so on.
However, this type of storage medium requires the use of a dedicated apparatus of complicated mechanism for reading and writing purposes. Thus, the system inevitably becomes bulky and expensive and the range of applications are limited as a result.
Another magnetic storage medium is a magnetic card. Magnetic cards have come into wide use recently. The magnetic card overcomes the foregoing disadvantages and is convenient for carrying by a person. However, since a magnetic recording is used, either the card or the magnetic head must be moved during the read and write operations. A driving system for this purpose is required. The durability of the driving system, and the durability of the magnetic cards themselves can present a problem. Further, since the read or write speed is limited by the mechanism, there is a fatal barrier to an increase in the storage capacity.
In order to overcome these deficiencies, memory devices have also been developed in which a semiconductor memory is contained in a case incorporating a back-up battery. Many of these devices use a conductive connector for connection with the main apparatus, thus giving rise to a reliability problem due to frequent connection and disconnection. Moreover, these devices are generally large in size so that the devices are not as easily portable as the previously mentioned magnetic cards, and their range of applications is limited.